Last Updated on April 10, by Chen
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Choosing between a journal bearing and roller bearing can be challenging. As mechanical engineers and designers with expertise in bearings, we know that the decision should not be taken lightly. The two options have distinct differences which must be considered before making an informed choice. In this article, we’ll break down the distinctions between these two types of bearings to help you decide which one is right for your project.
Journal bearings are comprised of a shaft rotating inside a housing or sleeve. This type of bearing does not use rolling elements like balls or rollers; instead, it works by rubbing against the inner surface of the housing. There are advantages to using this kind of simple design as well as challenges to consider when deciding whether it’s suitable for your application.
On the other hand, roller bearings make use of cylindrical rollers held together by spacers or cages in order to reduce friction and increase load capacity over journal bearing designs. These components provide superior performance characteristics but also come at a cost which needs to be weighed when choosing between them both.
We hope that after reading this article, you will have enough information to make an educated decision on whether a journal bearing or roller bearing is best suited for your specific application requirements.
Journal bearings offer a variety of advantages when compared to roller bearings. The first advantage is that they have high load capacity and can handle heavier loads without compromising performance, making them ideal for applications where other bearing types may fail due to their limited load capacities. Additionally, journal bearings are able to operate at higher rpm limits than roller bearings, allowing them to be used in more demanding applications. Finally, the selection criteria for journal bearings also tend to be simpler since they come in fewer shapes and sizes when compared with other types of bearings. This makes them easier to find the right size for any purpose. In terms of bearing selection criteria, journal bearings often prove superior in terms of both load capacity and rpm limits. Moving on from this section about the advantages of journal bearings, let’s now take a look at some disadvantages which could make it harder for you to decide if these are the best choice for your application needs.
Journal bearings are a veritable nightmare for mechanical engineers and designers. They can be an absolute catastrophe in terms of design, installation, noise, lubrication and cost. Here’s the lowdown on journal bearing disadvantages:
All in all, when considering whether or not journal bearings are worth pursuing for a given application one must weigh up the pros and cons carefully before making any decisions; however they remain popular solutions among many industries despite their drawbacks thanks largely in part to their versatility and relatively simple design components.
Roller bearings provide numerous advantages compared to traditional journal bearings, making them the preferred choice for many applications. They offer superior load-bearing capacity, higher speed capability and lower maintenance requirements than their counterparts. Additionally, roller bearings are more resistant to environmental conditions such as dust or temperature changes.
The above table illustrates the primary benefits of using a roller bearing over a journal bearing. When looking at longevity, roller bearings have far greater life expectancy; they also possess much higher load capacities while remaining capable of operating at high speeds with minimal maintenance needs. Furthermore, they are highly resilient against environmental factors like dust and temperature fluctuations which can cause significant damage to journal bearings in certain circumstances.
Overall, when choosing between journal and roller bearings it is important to consider all aspects of performance including durability, load capacity, high-speed capability and low-maintenance requirement along with any potential environmental influences that may arise in the application environment. These advantages make roller bearings an attractive option for most equipment designs where long service life and reliable operation are essential criteria for success.
The disadvantages of roller bearings can be likened to an unwelcome guest. They silently lurk in the background and make their presence known at the most inconvenient times – usually when you least expect it.
To begin, they are generally noisier than journal bearings. This is due to the higher friction between moving components that come with using roller bearing designs. Additionally, wear on these parts occurs more quickly over time due to this increased friction which leads to:
Finally, as a result of all these factors, choosing roller bearings should not be done lightly but rather after careful consideration of your specific application needs. Choosing the wrong type of bearing could lead to costly repairs in addition to downtime that may have been avoided had the right choice been selected from the start. The next section will discuss some important factors one must consider when selecting either a roller or journal bearing for any given project.
When choosing between a journal bearing and roller bearing, there are several factors to consider. Bearing type is the first factor that needs to be taken into account. Depending on the application, one type of bearing will work better than another. Load capacity should also be considered – both bearings have their own limits in terms of how much load they can handle before suffering mechanical failure or damage. Speed limits must also be assessed; any excessive speed may cause premature wear on certain components inside the bearing assembly. Temperature range is important too; some materials used for these types of bearings cannot operate within certain temperature ranges without being damaged over time. And finally, installation space should be examined as well – if the working area is cramped, this could restrict your choice of bearing size and design.
Overall, when selecting between journal and roller bearings, it’s best to assess each machine’s specific requirements related to the mentioned criteria so you can choose the right bearing for its intended purpose. Understanding all of these elements helps ensure that your selected bearing will function adequately throughout its entire lifespan with minimal maintenance required.
When choosing between a journal bearing and roller bearing, it is important to consider the load-bearing capacity of each. The following table provides an overview of key differences in load-bearing capacity:
Journal bearings are generally used for lighter loads that don’t require as much strength or weight support. Roller bearings, however, can handle heavier applications with larger amounts of weight and force. Depending on the size and type, some roller bearings have higher load capacities than others. Thus, depending on your application requirements, you may need to choose specific types of roller or journal bearings accordingly. Additionally, factors like ambient temperature, speed limits, and rotational speeds must be taken into account when making a decision about which type of bearing should be chosen.
Designing machines and equipment to accommodate rotating components often means selecting the correct bearing for the job. The choice between journal bearings or roller bearings can be made based on speed, load capacity, and operating temperature. Speed and RPM limits need to be taken into account when choosing a bearing type as well.
Journal bearings are generally recommended in applications that require low-speed rotations while still maintaining high torque ratings. These types of bearings have an unlimited maximum rpm limit but tend to work best in slower moving machinery with higher loads. On the other hand, roller bearings have a much lower torque rating, but they allow for greater speeds than journal bearings due to their ability to handle more rapid rotational movements without causing excessive wear on the bearing surfaces. Roller bearings typically have a maximum rpm limitation that should not be exceeded if extended life is desired from the product.
When considering both journal and roller bearing options, it’s important to consider machine-speed, maximum-rpm, rotational-speed, torque-rating, and expected bearing-life before making your selection. Factors such as these will help you determine which option is best suited for your particular application needs. Ultimately this decision will impact how successful your project is over time so take care when researching what solution works best for you!
Now that we have discussed the speed and RPM limits, let’s move on to operating temperature considerations when choosing between a journal bearing and a roller bearing. Temperature plays an important role in determining which type of bearing is best for your application. Bearing temperature must be kept within certain ranges as high temperatures can degrade performance or cause premature failure.
When selecting bearings, it is important to know the maximum-operating temperature rating of the bearings being considered. This information can usually be found in manufacturer product data sheets or catalogs. If this information is not available, you should contact the manufacturer directly. The manufacturer will also be able to provide specific temperature ratings based on their own testing results for each model they offer under different loading conditions. Generally, journal bearings can handle higher temperatures than roller bearings due to their larger surface area and better heat dissipation capabilities; however, this varies depending on lubrication requirements and other factors such as bearing size and material used.
It is also important to consider how the temperature range of the environment may affect bearing performance over time. You should make sure that any chosen bearing has enough margin in its rated temperature capacity versus expected operating temperatures for your application so that it does not reach its upper limit during normal operation or peak usage periods. Additionally, if extreme variations in environmental temperatures are anticipated (such as rapid changes from hot to cold), then more robust materials like stainless steel might need to be specified instead of softer metals like brass or aluminum alloys.
By understanding both speed/RPM limits and operating temperature requirements ahead of time, one can choose the right type of bearing with confidence knowing that it will perform optimally while meeting required specifications without exceeding its temperature rating limits. Therefore proper selection criteria upfront helps ensure optimum system performance throughout its lifetime with minimal maintenance requirements going forward.
When it comes to maintenance requirements, journal bearings and roller bearings differ significantly. Journal bearings require regular lubrication of the bearing surfaces and must be inspected regularly for signs of wear or damage. Roller bearings on the other hand typically need only periodic inspections since they are sealed units with their own lubricant supply that is usually sufficient throughout its service life. Additionally, installation of a journal bearing requires more attention than a roller bearing; alignment between components needs to be precise in order to ensure proper operation.
Conversely, installing a roller bearing is generally simpler because they are designed as self-aligning units. Bearing cleaning also differs; journal bearings often have crevices which can trap contaminants like dirt and dust particles, so thorough cleaning should be part of your maintenance routine when using this type of bearing. With roller bearings however, contaminant accumulation tends to be less of an issue due to the seals protecting the internal components from environmental conditions.
Considering these differences in terms of required care, one must weigh all factors before deciding whether a journal or roller bearing is suitable for their application. Size and installation space may further influence this decision…
When considering the maintenance requirements for a bearing, size and installation space are also key factors. Bearing size is affected by both the journal size and roller size, depending on which type of bearing you’ve chosen. For journal bearings, their longevity can be impacted if they aren’t sized correctly. Meanwhile, roller bearings require careful consideration when it comes to proper sizing for their axial or radial loads in order to prevent premature wear or failure.
The amount of space available in an application must also be taken into account when selecting a bearing. This will determine whether there is enough room to install the required bearing without issue. If not, then alternate solutions such as using split bearings may need to be considered instead.
In addition, considerations should be made regarding how easy it will be to perform regular inspections and lubrication with regards to any maintenance that needs doing on a particular bearing over its lifetime – especially where access is restricted due to tight spaces around the bearing installation area. Properly assessing all these factors prior to making your selection will help ensure that your choice of bearing meets all necessary requirements. With this information in hand, cost and availability can now come into play when deciding upon the ideal solution for a given application.
When it comes to making a decision between journal bearing and roller bearing, cost and availability are two of the most important factors. In one fell swoop, you can go from having an amazing project in your hands to being left with nothing but disappointment due to budget constraints or lack of stock availability – so let’s look at how these bearings compare on those fronts:
Overall then, there’s no clear winner across all categories when it comes to cost and availability – however knowing what your particular requirements are should help guide you toward selecting the right bearing for your job. With that in mind, we move on to looking at environmental conditions…
When considering a journal bearing versus roller bearing, environmental conditions are an important factor to consider. Many of these applications require long-term reliability and robust operation in extreme temperatures, humidity levels and vibration exposures. To ensure the correct application is chosen for each specific environment, it’s vital to assess the requirements against both types of bearings.
These features allow us to compare different materials and decide which one best meets our needs based on the environmental conditions we must operate within, ensuring reliable operation and minimizing downtime caused by component failure due to incorrect selection criteria being applied initially.
When it comes to choosing between journal bearings and roller bearings, quality assurance standards are an essential factor for consideration. Ensuring the necessary bearing performance requires a comprehensive approach to bearing quality assurance that covers all aspects of design, production, and operation. Bearing testing standards must be established at each stage which includes manufacturing, installation, operation, and maintenance in order to guarantee proper function.
Manufacturers should adhere to strict bearing manufacturing standards such as those outlined by leading industry organizations like ISO, ANSI/ABMA, or AGMA. This includes standardizing parts materials with clear specifications regarding hardness measurements and other characteristics related to strength and durability. All components must meet specific dimensional tolerances set by these guidelines and accepted practices before any assembly can begin.
Furthermore, the quality control process must involve thorough inspection throughout every step of the manufacturing process – from raw material selection through finished product delivery – using advanced visual assessment technologies such as optical microscopes or computed tomography scans (CT scans). The end goal is obviously to ensure that only high-quality products make their way into circulation but also have them live up to their designed purpose when put in use.
Once assembled correctly according to the highest possible quality assurance standards, one may confidently choose either journal or roller bearing depending on the requirements at hand. As we move forward into the next section about design considerations, it’s important that manufacturers understand how various factors influence optimal functioning so they can make informed decisions about what type of bearing best suits their needs.
When it comes to choosing between a journal bearing and a roller bearing, there are several design considerations that must be taken into account. Firstly, the installation requirements of each type of bearing can vary significantly. Generally speaking, journal bearings require more sophisticated installation techniques than roller bearings do. Secondly, lubrication is an important factor when selecting a bearing as different types require various amounts and types of lubricants in order to function correctly. Thirdly, load capacity is another key consideration; typically roller bearings have higher load capabilities compared to journal bearings. Finally, temperature limits should also be considered—roller bearings tend to operate better at higher temperatures when compared with journal bearings.
In terms of design considerations for selecting a bearing, proper installation technique is critical for ensuring optimal performance and longevity from the part. Furthermore, understanding the materials and lubrication requirements is necessary for achieving reliable operation over time. With regard to load capacities and temperature limits, it’s essential to consider these factors according to the specific application before making a selection. Ultimately, careful evaluation of these different elements will help ensure that you select the best possible solution for your needs.
In conclusion, when it comes to choosing between a journal bearing or roller bearing for your application, there are many factors to consider. Firstly, the cost and availability of each type must be taken into account as well as any environmental conditions they may encounter in their expected environment. Quality assurance standards should also be considered so that you can rest assured that whichever one you choose will have been produced with precision. Lastly, design considerations such as load capacity and speed requirements should be evaluated in order to make an informed decision about which type of bearing is best suited for your needs. By carefully weighing all these aspects we can ensure our projects run smoothly like clockwork – providing us peace of mind that our applications will deliver optimal results efficiently and safely.
Journal or plain bearings consist of a shaft or journal which rotates freely in a supporting metal sleeve or shell. There are no rolling elements in these bearings. Their design and construction may be relatively simple, but the theory and operation of these bearings can be complex.
This article concentrates on oil and grease-lubricated full fluid film journal bearings; but first a brief discussion of pins and bushings, dry and semilubricated journal bearings, and tilting-pad bearings.
Low-speed pins and bushings are a form of journal bearing in which the shaft or shell generally does not make a full rotation. The partial rotation at low speed, before typically reversing direction, does not allow for the formation of a full fluid film and thus metal-to-metal contact does occur within the bearing. Pins and bushings continually operate in the boundary lubrication regime.
These types of bearings are typically lubricated with an extreme pressure (EP) grease to aid in supporting the load. Solid molybdenum disulfide (moly) is included in the grease to enhance the load-carrying capability of the lubricant.
Many outdoor construction and mining equipment applications incorporate pins and bushings. Consequently, shock loading and water and dirt contamination are often major factors in their lubrication.
Figure 1. Kingsbury Radial
and Thrust Pad Bearing
Dry journal bearings consist of a shaft rotating in a dry sleeve, usually a polymer, which may be blended with solids such as molybdenum, graphite, PTFE or nylon.
These bearings are limited to low-load and low-surface speed applications. Semilubricated journal bearings consist of a shaft rotating in a porous metal sleeve of sintered bronze or aluminum in which lubricating oil is contained within the pores of the porous metal. These bearings are restricted to low loads, low-to-medium velocity and temperatures up to 100°C (210°F).
For more information, please visit Industrial Combined Journal Bearings.
Tilting-pad or pivoting-shoe bearings consist of a shaft rotating within a shell made up of curved pads. Each pad is able to pivot independently and align with the curvature of the shaft. A diagram of a tilt-pad bearing is presented in Figure 1.
The advantage of this design is the more accurate alignment of the supporting shell to the rotating shaft and the increase in shaft stability which is obtained.1
Journal bearings are meant to include sleeve, plain, shell and babbitt bearings. The term babbitt actually refers to the layers of softer metals (lead, tin and copper) which form the metal contact surface of the bearing shell. These softer metals overlay a stronger steel support shell and are needed to cushion the shell from the harder rotating shaft.
Simple shell-type journal bearings accept only radial loading, perpendicular to the shaft, generally due to the downward weight or load of the shaft. Thrust or axial loads, along the axis of the shaft, can also be accommodated by journal bearings designed for this purpose. Figure 1 shows a tilt-pad bearing capable of accepting both radial and thrust loads.
Figure 2. Layers of Journal Bearing Structure
Journal bearings operate in the boundary regime (metal-to-metal contact) only during the startup and shutdown of the equipment when the rotational speed of the shaft (journal) is insufficient to create an oil film. It is during startup and shutdown when almost all of the damage to the bearing occurs.2
Hydrostatic lift, created by an external pressurized oil feed, may be employed to float large, heavy journals prior to startup (shaft rotation) to prevent this type of damage. During normal operation, the shaft rotates at sufficient speed to force oil between the conforming curved surfaces of the shaft and shell, thus creating an oil wedge and a hydrodynamic oil film.
This full hydrodynamic fluid film allows these bearings to support extremely heavy loads and operate at high rotational speeds. Surface speeds of 175 to 250 meters/second (30,000 to 50,000 feet/minute) are common. Temperatures are often limited by the lubricant used, as the lead and tin babbitt is capable of temperatures reaching 150°C (300°F).
It is important to understand that the rotating shaft is not centered in the bearing shell during normal operation. This offset distance is referred to as the eccentricity of the bearing and creates a unique location for the minimum oil film thickness, as illustrated in Figure 3.
Figure 3. Shaft Motion During Startup
Normally, the minimum oil film thickness is also the dynamic operating clearance of the bearing. Knowledge of the oil film thickness or dynamic clearances is also useful in determining filtration and metal surface finish requirements.
Typically, minimum oil film thicknesses in the load zone during operation ranges from 1.0 to 300 microns, but values of 5 to 75 microns are more common in midsized industrial equipment. The film thickness will be greater in equipment which has a larger diameter shaft.
Persons requiring a more exact value should seek information on the Sommerfeld Number and the Reynolds Number. Discussion of these calculations in greater detail is beyond the scope of this article. Note that these values are significantly larger than the one-micron values encountered in rolling element bearings.
The pressures encountered in the contact area of journal bearings are significantly less than those generated in rolling bearings. This is due to the larger contact area created by the conforming (similar curvature) surfaces of the journal and the shell.
The mean pressure in the load zone of a journal bearing is determined by the force per unit area or in this case, the weight or load supported by the bearing divided by the approximate load area of the bearing (the bearing diameter times the length of the bearing). In most industrial applications, these values range from 690 to 2,070 kPa (100 to 300 psi).
At these low pressures, there is virtually no increase in the oil viscosity in the bearing contact area due to pressure. Automotive reciprocating engine bearings and some severely loaded industrial applications may have mean pressures of 20.7 to 35 MPa (3,000 to 5,000 psi). At these pressure levels, the viscosity may slightly increase. The maximum pressure encountered by the bearing is typically about twice the mean value, to a maximum of about 70 MPa (10,000 psi).
Oil whirl is a phenomenon that can occur in high-speed journal bearings when the shaft position within the shell becomes unstable and the shaft continues to change its position during normal operation, due to the fluid forces created within the bearing. Oil whirl may be reduced by increasing the load or changing the viscosity, temperature or oil pressure in the bearing.
A permanent solution may involve a new bearing with different clearances or design. Oil whip occurs when the oil whirl frequency coincides with the system’s natural frequency. The result can be a catastrophic failure.3
Oils are used in journal bearings when cooling is required or contaminants or debris need to be flushed away from the bearing. High-speed journal bearings are always lubricated with oil rather than a grease. Oil is supplied to the bearing by either a pressurized oil pump system, an oil ring or collar or a wick. Grooves in the bearing shell are used to distribute the oil throughout the bearings’ surfaces.
The viscosity grade required is dependent upon bearing RPM, oil temperature and load. The bearing speed is often measured strictly by the revolutions per minute of the shaft, with no consideration of the surface speed of the shaft, as per the “ndm” values calculated for rolling bearings. Table 1 provides a general guideline to selecting the correct ISO viscosity grade.
The ISO grade number indicated is the preferred grade for speed and temperature range. ISO 68- and 100-grade oils are commonly used in indoor, heated applications, with 32-grade oils being used for high-speed (10,000 RPM) units and some outdoor low-temperature applications.
Note in the table that the higher the bearing speed, the lower the oil viscosity required; and that the higher the operating temperature of the unit, the higher the oil viscosity that is required. If vibration or minor shock loading is possible, a higher grade of oil than the one indicated in Table 1 should be considered.
Bearing Speed Bearing / Oil Temperature (°C) (rpm) 0 to 50 60 75 90 300 to 1,500 - 68 100 to 150 - ~1,800 32 32 to 46 68 to 100 100 ~3,600 32 32 46 to 68 68 to 100 ~10,000 32 32 32 32 to 46Table 1. Journal Bearing ISO Viscosity Grade Selection
Another method of determining the proper viscosity grade is by applying minimum and optimum viscosity criteria to a viscosity-temperature plot. A generally accepted minimum viscosity of the oil at the operating temperature for journal bearings is 13 cSt, although some designs allow for an oil as thin as 7 or 8 cSt at the operating temperature.
The optimum viscosity at operating temperature is 22 to 35 cSt, for moderate-speed bearings if no shock loading occurs. The optimum viscosity may be as high as 95 cSt for low-speed, heavily loaded or shock-loaded journal bearings.
Using this method requires some knowledge of the oil temperature within the bearing under operating conditions, which can be difficult to determine. Fortunately, an accurate oil temperature is not needed for most viscosity determinations. It is common to determine the temperature of the outer surface of the pipes carrying oil to and away from the bearing.
The temperature of the oil inside of the pipes will generally be higher (5 to 10°C, 10 to 18°F) than the outer metal surface of the pipe. The oil temperature within the bearing can be taken as the average of the oil entering versus the temperature exiting the bearing.4
A third and more complex method is to calculate the oil viscosity needed to obtain a satisfactory oil film thickness. Persons wishing to learn more about this method should seek information regarding the Sommerfeld equation and either eccentricity ratios or Reynolds Numbers.4
If the oil selected is too low in viscosity, heat will generate due to an insufficient film thickness and some metal-to-metal contact will occur. If the oil is too high in viscosity, heat will again be generated, but due to the internal fluid friction created within the oil. Selecting an oil which is too high in viscosity can also increase the likelihood of cavitation.
The high- and low-pressure zones, which are created within the oil on each side of the area of minimum film thickness, can cause oil cavitation in these bearings. Cavitation is a result of expansion of dissolved air or a vapor (water or fuel) in the low-pressure zone of the bearing.
The resulting bubble implodes, causing damage, as it passes through the high-pressure portion of the bearing. If the implosion or collapse of the vapor bubble occurs next to the metal surface, this can cause cavitation pitting damage to the metal. If the implosion of the bubble occurs within the oil, a micro hot spot or micro-dieseling can occur, which may lead to varnishing within the system.
Typically, a rust and oxidation (R&O) inhibited additive system is used in the oils employed in these applications. Antifoam and pour point depressant additives may also be present. Antiwear (AW) hydraulic oils may also be used as long as the high-temperature limit of the zinc AW component is not exceeded and excessive water is not present.
R&O oils tend to have better water separation characteristics, which is beneficial, and the AW properties of a hydraulic oil would be beneficial only during startup and shutdown, assuming a properly operating bearing.
Grease is used to lubricate journal bearings when cooling of the bearing is not a factor, typically if the bearing operates at relatively low speeds. Grease is also beneficial if shock loading occurs or if the bearing frequently starts and stops or reverses direction.
Grease is almost always used to lubricate pins and bushings because it provides a thicker lubricant than oil to support static loads and to protect against vibration and shock-loading that are common in many of these applications.
Lithium soap or lithium complex thickeners are the most common thickeners used in greases and are excellent for most journal bearing applications. The grade of grease used is typically an NLGI grade #2 with a base oil viscosity of approximately 150 to 220 cSt at 40°C.
Greases for low-speed, high-load, high temperatures and for pins and bushings may use a higher viscosity base oil and be formulated with EP and solid additives. Greases for improved water resistance may be formulated with heavier base oils, different thickeners and special additive formulations.
Greases for better low-temperature dispensing may incorporate a lower viscosity base oil manufactured to an NLGI #1 specification. Bearings lubricated by a centralized grease dispensing systems typically use a #1, 0 or 00 grade of grease.
The apparent viscosity of grease changes with shear (pressure, load and speed) that is, greases are non-Newtonian or thixotropic. Within a rotating journal bearing, as the bearing rotates faster (shear rate increases), the apparent viscosity of the grease decreases and approaches the viscosity of the base oil used in grease.
At both ends of the bearing shell, the pressure is lower and therefore the apparent viscosity remains higher. The resulting thicker grease at the bearing ends acts as a built-in seal to reduce the ingression of contaminants.
The greasing procedures for journal bearings and pins and bushings are not as well-defined or as critical as for rolling bearings because the grease is not subjected to the churning action created by the rolling elements.
The volume of grease to inject and the frequency of application are dictated more by trial and error. Generally, most journal bearings cannot be overgreased. Caution must be taken when pumping grease into a bearing that is fitted with seals, so they are not damaged or displaced by the force and volume of the incoming grease.
The harshness of the environment, shock loading and especially the operating temperature will be major factors in determining the frequency of relubrication.
Journal bearings are generally a simpler design and not as difficult to lubricate as rolling element bearings. The proper viscosity matched to the operating conditions and a clean and dry lubricant will usually suffice to form a full fluid lubricating film and provide excellent bearing life.
References
Strecker, William. “Troubleshooting Tilting Pad Thrust Bearings.” Machinery Lubrication magazine, March-April .
Strecker, William. “Failure Analysis for Plain Bearings.” Machinery Lubrication magazine, July-August .
Berry, James. “Oil Whirl and Whip Instabilities within Journal Bearings.” Machinery Lubrication magazine, May-June .
Tribology Data Handbook. Chapter 61, Journal Bearing Design and Analysis. Khonsari, M. CRC Press, .
Editor’s Note:
Portions of this article have been previously published in the Society of Tribologists and Lubrication Engineers (STLE) Alberta Section, Basic Handbook of Lubrication, Second Edition, .